Dust brush



FIG. 1 is a perspective view of a dust brush in accordance with the present invention;

FIG. 2 is a side view of the dust brush, the opposite side view being a mirror image thereof; and,

FIG. 3 is a front view thereof, the back view being a mirror image thereof.

The broken lines represent brush fibers, which do not form part of the claimed design. 

The ornamental design for a dust brush, as shown and described. 